Syrian Kurds say they cannot hold foreign IS militants indefinitely

Kurdish-led authorities controlling northeastern Syria will not be able to hold foreign Islamic State (IS) group militants indefinitely, and their home countries should take them back, a senior official there said on Thursday.

Abdulkarim Omar, joint head of foreign relations in the area, told journalists that its administration was holding about 500 foreign fighters and 500 family members from some 40 countries, after last year's defeat of IS in most of the territory it once held in Syria and Iraq.

"For us it is a very large number because these Daeshis are dangerous and they committed massacres, and their presence in our detention is an opportunity for the international community to put them on trial," Omar said, using a colloquial Arabic term for IS members.

Backed by the United States and its allies, the Kurdish-led Syrian Democratic Forces (SDF) militia alliance has captured swathes of northern and eastern Syria from IS over the past two years, including the militants' one-time capital Raqqa.

The SDF is now fighting to take the last few villages IS holds along the Euphrates River in Syria, close to the border with Iraq, and has detained more foreign fighters, Omar said.

Omar said the administration in the area lacks the resources to properly rehabilitate so many prisoners. It will put Syrians on trial, but not foreigners, and it will not execute anyone as it did not impose the death penalty, he added.

"We will try the path of dialogue... to hand them over to their countries, but if our hope is cut, we will have other options," he said. He declined to explain what he meant by "other options," apart from no longer detaining the prisoners.

Omar spoke at a news conference in Qamishli near the Turkish border, to announce that Sudan was taking back a captured Sudanese woman who had joined IS.

She was one of only 50 or 60 people taken back by their countries so far, including women and children, Omar said. He said Russia and Indonesia had each taken back families.

The continued presence of foreign fighters in an unstable part of the world poses a danger to the whole international community because they might take advantage of any new period of chaos to escape, Omar said.

"We alone cannot bear this burden," he said. 

Last year, French defence minister, Florence Parly, said she did not want French IS fighters to return, and it would be "best" for them to die in the field.

Weeks later, Parly's British counterpart, Gavin Williamson, said "a dead terrorist can't cause any harm to Britain," and that British IS fighters should be hunted down and killed, instead of returning home.

The United States has transferred and charged two of its citizens who were captured by the SDF.

In July, the UK Home Office suspended legal cooperation with the United States in the cases of two alleged IS group militants raised in Britain over concerns that they may face the death penalty in US courts.

The men are accused of belonging to the so-called IS "Beatles" cell, which was allegedly involved in executing Western hostages.